[ARC5] Use of a Variac

[Dennis Monticelli]

The half line voltage is necessary to get the rectifier(s) warm enough to
pass current to the filter capacitors.  But after that plateau it makes
more sense to ramp up the voltage in steps vs waiting 30 min and then
taking it to full line voltage.

Dennis AE6C

On Thu, Apr 23, 2020 at 1:18 PM Robert Eleazer <releazer at earthlink.net>
wrote:

> We frequently hear people suggest that you bring up the input voltage on
> an older piece of equipment with a variac to allow capacitors to fromate
> and so forth.  Of course this remains as a somewhat controversial approach.
>
> I have a URM-127 that I need to recalibrate the frequency dial and in the
> process of researching that procedure I found the following:
>
> *a. *If the signal generator has been stored in excess of two years,
> perform the following pre-test procedure to assure proper operation of the
> power supply filter capacitor.
>
> (1) Operate the signal generator for 30 minutes at 57.5 VAC, 60-400 Hz, 1
> phase input.
>
> (2) Adjust the input to the required value using a variable transformer
> between the power supply and the power cable. Check input voltage prior to
> connecting to the signal generator.
>
> (3) Remove the variable transformer from the power cable and connect the
> power cable to the electrical power source.
>
> Wayne
>
> WB5WSV
>
>
>
>
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